The invention relates to osteosynthesis devices.
Document EP-0 778 007-A1 discloses a backbone osteosynthesis device comprising a rod, a cross-member, a connector, a ring, and a nut. The connector has two jaws adapted to clamp on the rod. It has a housing for receiving the cross-member which extends in a direction that is perpendicular to the rod received between the jaws. The connector is threaded to receive the nut. To assemble the device, the jaws are clipped on the rod, then the ring is engaged on the connector so that it bears against the jaws. The cross-member is inserted in the housing. Finally, the nut is tightened onto the connector. The nut applies thrust to the cross-member so that it bears against the ring. By having inclined faces to provide contact between the ring and the jaws, the ring in turn urges the jaws towards each other so as to clamp onto the rod. Such a device makes it possible to connect a longitudinal rod rigidly to a cross-member, and more generally such devices make it possible for common cross-members to unite two longitudinal rods which extend generally in parallel along the spinal column with each of them connected to the spinal column. Nevertheless, that device has a large number of parts. A large number of individual acts are required to install it and it is relatively complicated to mount.
An object of the invention is to provide a device which can be mounted more quickly and more simply.
To achieve this object, the invention provides a connector for a backbone osteosynthesis device, the connector having two jaws and presenting a housing adapted to receive a rod bearing against the jaws, the connector being arranged so that force on the rod received in the housing and acting towards the jaws urges the jaws towards each other, wherein the connector is made as a single piece.
Thus, the osteosynthesis device has a small number of parts. The number of individual assembly operations to be performed prior to the surgical operation or during the surgical operation is thus reduced, and mounting of the device is simplified.
Advantageously, the connector includes at least one junction contiguous with the jaws, the junction being of a width that is smaller than the width of the connector level with the jaws.
The elastic flexibility of the jaws relative to the remainder of the connector is thus increased without any need to give large dimensions to the connector in order to achieve equivalent flexibility.
Advantageously, the junction has a notch extending from the jaws in the opposite direction to the jaws.
This further increases the flexibility of the jaws.
Advantageously, the connector has a head connected to the jaws by the junction, the width of the junction being less than the width of the head.
Thus, if the head is to receive a clamping member, the dimensions of the head can be large so as to make it easier to manufacture.
Advantageously, the connector is arranged in such a manner that the rod received in the housing bears against respective zones of the jaws that are remote from the junction.
Thus, the lever arm exerted by the transverse rod on the jaws is increased, thereby increasing the clamping of said jaws on the longitudinal rod.
Advantageously, the connector is arranged in such a manner that the rod received in the housing bears against respective edges of the jaws that are remote from the junction.
Advantageously, each of the jaws presents a plane face adapted to extend facing the rod received in the housing, said face sloping towards the inside of the connector.
Advantageously, the connector has a threaded face, the housing extending between the jaws and the threaded face.
Advantageously, the threaded face is formed by a duct extending inside the connector.
This prevents the thread from being exposed on the outside and does not give rise to injury to the body suffering arthrodesia.
The invention also provides an osteosynthesis device comprising first and second rods, a threaded member, and a connector having two jaws adapted to clamp onto the first rod, the connector having a threaded face and a housing extending between the jaws and the threaded face and adapted to receive the second rod bearing against the jaws, the connector being arranged so that a force applied by the threaded member co-operating with the threaded face, against the second rod received in the housing towards the jaws urges the jaws towards each other so as to clamp onto the first rod, wherein the connector is made as a single piece.
Advantageously, the jaws are adapted to be clipped onto the first rod.
Advantageously, the jaws are adapted to clamp onto the first rod in the absence of any force being applied to the jaws.
Advantageously, the jaws are configured in such a manner that the first rod projects from the jaws in a radial direction of the first rod when the first rod is received between the jaws.
It is thus pointless to provide a large gap between the rod and the body suffering from arthrodesia. The device can thus be placed very close to the body.
Advantageously, the first rod forms a link between vertebrae along a backbone, and the second rod forms a transverse union between the first rod and another rod forming a link between vertebrae.
Advantageously, the connector is arranged so that the second rod can be received in the housing while occupying a range of angular positions about a direction perpendicular to the first rod.
It is thus possible at will to adapt the relative position of the two rods to the configuration of the device mounted on the patient.